How Long Does Naloxone Stay in Hair follicles?
Evidence-based answer reviewed against SAMHSA cutoffs and FDA assay documentation · Updated September 2026
Quick answer: Most people clear Naloxone from hair follicles within n/a of last use — heavy or daily use stretches that window substantially. Never screened on any standard or expanded employment panel.
Naloxone detection windows by test type
Each specimen tells a different story because each samples different biology:
| Test type | Typical Naloxone detection window |
|---|---|
| Urine | any: not tested / no interference |
| Saliva (Mouth Swab) | any: n/a |
| Hair Follicles | n/a |
| Blood | any: n/a |
("Hair testing reads a 90-day archive: drugs enter the shaft via the bloodstream during growth (~0.5 inch/month), locking in use-history that washing can't erase. Head hair standard segments assume 1.5-inch cuts; body hair extends lookback unpredictably. Single exposures sometimes fall below segment thresholds — chronic use writes loud chapters.",)
Why detection works this way
Naloxone is an opioid antagonist used to reverse opioid overdoses — it is not a drug of abuse and produces no intoxication. It appears on no standard or expanded drug panel, and it does not cause positives for opioids or any other screened drug.
If you administered naloxone to someone else (or received it yourself during an overdose), it will not show up on your own drug test. The only interaction to know about is medical, not testing: naloxone can precipitate withdrawal in opioid-dependent people.
The 'does Narcan show up on a drug test' question is common because people carry or administer it in emergencies. The answer is no: no panel screens for it, and it has no cross-reactivity with any standard immunoassay.
Testing cutoffs in plain language
Never screened on any standard or expanded employment panel. A specimen under the initial cutoff reports negative without further work; a screen above cutoff gets confirmed by mass spectrometry before anyone sees a positive.
Planning ahead? Our at-home drug test guide covers retail kits that mirror lab screens.
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Does Naloxone Show up on a Drug Test?
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Can Narcan Cause a Positive Drug Test?
Can Naloxone trigger a false positive? Cross-reactivity evidence, confirmation testing, and how to clear your name with the MRO. Full guide →
Naloxone Drug Test Guide: Panels, Detection Windows & More?
Complete Naloxone drug test guide: which panels detect it, urine/hair/saliva/blood detection windows, cutoff levels and prescription verification. Full guide →
How Long Does Naloxone Stay in Urine?
How long Naloxone stays detectable in urine — urine, hair, saliva & blood windows explained with cutoffs. Full guide →
Do prescriptions count against me?
No — verified prescriptions report as negative through the Medical Review Officer. Declare medications at collection and answer the follow-up call.
Sources & further reading
- SAMHSA — Mandatory Guidelines for Federal Workplace Drug Testing Programs (cutoffs, MRO process)
- DOT — 49 CFR Part 40 procedures for transportation workplace testing
- Brahm NC et al., Mayo Clinic Proceedings 2008;83(1):66–76 — false-positive cross-reactivity reference
- FDA — drug-of-abuse test device labeling (detection window conventions)